ghc-options: Utilities for extracting GHC options needed to compile a given Haskell target.

ghcopts is a library that makes it easy to determine what
GHC options are needed to compile a file. It was built
by extracting the relevant code from hdevtools which
queries cabal and stack to determine the locations
of various package databases, in order to pass them to
GHC to process a target file. We have refactored this
code into a separate package so that it can be used by
other tools built on the GHC API.